Vent for pumps



C. w. GINTER vEN'r Fon PuuPs Septk 19,I 1.950

Filed July 9. 1947 SePt- 19, 1950 c. w. GlNTER 2,522,711

VENT FOR PUMPS Fled'Jly 9, 1947 3 Sheets-Sheet 2 c. w. G'INTER 2,522,71 l

VENTFOR PUMPS 3 Sheets-Sheet 3 Sept. 19,v 1950 fig/.

Patented Sept. 19, 1950 Charles W. Ginteig Bryan, Ohio, assignor to The Aro Equipment Corporation, Bryan, Ohio, a

corporation of 1Ohio Application July 9, 1947, serial No. 759,741-

13 Claims. 1101. 1oz-203)' This invention relates to a vent for a 1pu1mp for pumping liquid, such as lubricating oil, and more particularly to such pumps for use in conjunc= tion with a device for metering or measuring the amount of liquid pumped.

It is an object of the invention to remove substantially all the air or other gases fromthe liquid to be pumped through the meter, so that only liquid` is measured on the meter. This is particularly important because the amount for the liquid dispensed is paid for by a customer depending on the meter reading, and accuracy is essential.

It is another object of the invention to provde an improved vent for a liquid pump which functions to prevent pumping of air or gas when the supply in the container from which the Iiuid is pumped gets low.

It is also an object of the invention to return any air or gas which passes the foot valve of a iiuid pump to the liquid below the foot valve and outside the confines of the pump.-

It is a further object of the invention to provide an air or gas vent for a fluid pump in which the air or gas is vented through a hollow tube extending from and through the piston valve stem to a position below the foot valve.

It is another object of the invention to provide a valve stem in the form of a hollow rod which is of novel notched design to permit the passage of air and some oil therethrough if` air passes into the pump chamber above the foot valve.

With these and other objects in Viewl the invention consists in the construction, arrangement and combination of the various parts of my de-l vice whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in the claims and illustrated in the accompanying drawings, wherein:

Figure l is a vertical sectional view of the lower `portion of a lubricant pump.

vFigure 2 is a partial vertical sectional View of the lubricant pump piston valve stem and hollow air vent tube, taken with the same parts shown in Figure 1 rotated 90 about their vertical axis.

Figure 3 is a horizontal sectional view taken on line 3-3 of Figure 1; n

Figure 4 is Va horizontal sectional view taken on line 4-4 of Figure 1;

U Figure 5 is a section view taken on line 5-5 of Figure 25 and Figure 6 is aV sectional view of a hollow valve stem and hollow tube assembly illustrating another embodiment of the invention.

Figure `7 is a partial sectional view of the device shown in Figure 6 with the same parts with some parts shown in elevation instead of in section and with the piston in an upper position; n Figure 8 is a horizontal sectional view taken on line 8`8 of Figure 6;

Figure 9 is a vertical sectional View of a third embodiment of the invention; and

Figure l0 is a sectional view taken on line ioln of Figure 9. p

Referring specifically to Figures lI to 5, ind elusive, for a detailed description of the first embodiment of the invention. numeral 21D designates a cylinder for the pump having a foot valve, generally indicated at 2| at the bottom thereof. vThe foot `valve 2| lextends into the liquid to be pumped from aliquid container i9 and is positioned adjacent the bottom thereof. The foot valve 2| comprises a relatively heavy valve plate 23 which seats by gravity on a valve seat 22. n n

A piston generally indicated at 24 reciproca-tes in the cylinder 2|) and includes an upperI portion 25 which is connected to a suitable reciprocating piston rod 45. The piston 24 divides the cylinder into an upper pressure chamber 26 and a lower inlet chamber 21.` A chamber 2li is formed below the f oot valve plate 23. A vertically extending generally cylindrical rod 29 is slidably mounted on` the foot valve plate at 3|] and extends therethrough so that a portion is positioned in the chamber 28 below the foot valve plate 23 and the major portion is positioned in the chamber `2'| above the foot Valve plate` 23 when the piston 24 is in its upper position, as shown in Figures land .2st The rod 29 is provided with a central bore 3| extending through: out its length and with a flat 32 which extends from the topof the rod to a` point just above the valve plate 23.

' 24 and is biased toward a piston valve seat 3l by a compression spring 36'. rIhe piston valve plate 35 is secured to a piston valve stem 3B which is hollow `and forms a closed chamber 39, with the hollow portion of the piston 24 which forms a chamber 4| communicating with `chamber 39. it is understood thatthe piston rod 45 is secured to the upper porton ,2510i piston '24 in a uid` tight manner. Portion 25 isalso provided with an internal shoulder 40 to limit the upward movement of valve stem 38.

The `piston 24 has a rweb 42 connecting' the piston portion and the upper portion 25 thereof through threads 44, which web is open toupper cylinder chamber `26, as is apparent `from the drawing. It is. to be noted that `the piston valve plate 35 is provided with a central aperture 43 through which the hollow rod 29 extends with considerable clearance.

Referring now to Figures 6, 'i yand 8 for a detailed description of a second embodiment of the invention, numeral I designates a cylinder having a foot valve generally indicated at 52 disposed adjacent the bottom thereof. The cylinder and foot valve are adapted to be inserted in a container, such as shown at I9 in Figure l, and to extend almost tothe bottom thereof, as shown in that figure. A piston generally indicated at 53 divides the cylinder 5I into an upper pressure chamber 54 and a, lower inlet chamber 55, it being noted that the piston 53 is shown in a lower position in Figure 6 and in an upper position in Figure 7.

The foot valve comprises a relatively heavy valve plate 56 seated by .gravity on a seat 51. A chamber 58 is iormedby the casting forming the valve seat below the foot Valve plate 56.

The piston 53 comprises a main piston member 59 including suitable packing 9 I, which main piston 59 is secured to a hollow casting 62 which forms an open chamber 63 communicating with chamber 55 and also provides a valve seat 64 for an annular piston valve member 65. The piston valve member 95 is biased toward its seat by a compression spring 66. An elongated casting 68 is secured to the hollow seat casting 62 by cooperating threads 99 at one end thereof, and is secured to a reciprocating piston rod 1| by cooperating threads 12 at the other end thereof. The casting 68 is hollow and provides an elongated chamber 13 therein, which chamber is open at its lower' portion and communicates with pressure chamber 54 by reason of .apertures 14 in the casting and webs 15 which connect with the piston valve seat member 62 and for-m the lower portion of casting 68.

The piston rod 1|V extends through an upper cylinder casting 16 and connects to suitable reciprocating mechanism (not shown). An outlet passage 11 for the fluid pumped is provided in the upper cylinder casting 16 ,and a packing 18 surrounds the piston rod 1 I.

A hollow piston Valve stem 19 is connected to the piston valve member 65 and reciprocates therewith within the chamber 13. A plug 8| is osecured to the top of the valve stem 19 in a fluid slot or notch 85' is cut in its upper portion. Furtherrnore, the external diameter of 'the rod 83 is somewhat smaller than the internal diameter of the valve stem 19, providing a clearance space therebetween indicated at 86. Obviously, the Valve stem 19 and the hollow rod 83 are reciprocable rela-tive to each other, without interference.

Referring specifically to Figures 9 and 10 for a detailed description of the third embodiment of the invention, a sirnilar type pump is shown for disposition in a closed vessel 9| containing liquid to be pumped, and numeral 92 designates a cylinder having a ioot valve 93 seated at 94 on a member 95 at the bottom of the cylinder 92. The cylinder 92 is adapted to extend into the container 9| adjacent the bottom thereof.

A piston generally indicated at 9G divides the cylinder 92 into an upper pressure chamber 91 and a lower inlet chamber 98. A chamber 99 is formed by member 95 beneath the valve seat and ports IIlI are formed in member 95'.

The piston 96 comprises a main piston member |92 including suitable packing |93, which main piston member is secured to a hollow seat casting |04 forming an opening |95 communicating with inlet chamber 98 and also providing a valve seat |96 for an annular piston valve member |91.

The piston valve member |91 is biased toward its seat |96 by a relatively strong compression spring |93. An elongated casting |99 is secured to the seat casting |94 by screw threads III. The casting |99 is open at its bottom and provides an elongated chamber II2 therein communicating with pressure chamber 91 by reason of openings I I3 in the casting |99. A piston rod H4 extends through an upper cylinder casting IE5 and connects to a suitable manual, mechanical or electrical reciprocating mechanism (not shown). Suitable outlet passages and a meter, such as shown at 99 in Figure 7, are also provided, but are not shown.

A hollow piston valve stem H6 is connected to the piston valve member |91 and reciprocates therewith in chamber I I2. A plug Il! closes the top of the valve stem I IE in a iluid tight manner and provides a chamber IIB. It is to be noted that chamber |I8 is in substantially free and open communication with passageway |95 in casting |94 and with the inlet chamber 93 in cylinder 92.

A hollow rod II9 extends downwardly through the foot valve plate 95 intor the chamber 99 and is preferably slidably mounted onr the foot valve Iplate 95. The rod ||9 also extends upwardly through chamber 98, hollow casting |94 and into chamber IIS formed by the valve stem H6. The rod |I9 is spaced a considerable dista-nce from the piston valve |91, seat |96 and piston valve stem I I6. The rod II9 is provided with a hollow bore |2I. Obviously, the valve stem IIS and the hollow rod ||9 are reciproca-ble relative to each other without interference.

Operation of Figures 1 to 5 Assuming that the liquid level in the container I9 is at the position shown in Figure l, and the piston rod 45 is being reciprocated, the piston 2t will move upwardly to force liquid under pressure from upper chamber 26, at the same time causing a reduction in lpressure in lower chamber 21. The foot valve plate 23 will, therefore, be raised from its seat 22 and liquid will enter chamber 21 from container I9 through ports 22a in the foot valve.

When the piston 24 is moved downwardly, the foot valve plate 23 is closed and the piston valve member 35 is lifted from its seat 51 against the bias of spring 36, whereupon liquid from chamer 21 passes through chamber 33, past the piston Valve member 35, through the openings between web 42 and into chamber 2B. Obviously, when the piston 24 begins its upward movement, the piston valve member 35 is again seated and liquid is prevented from flowing between chambers 25 and 21.

During the downward stroke of piston 2d, some liquid will pass from the lower chamber 2l',` through the aperture 43 in the piston valve member 35, past the flat portion 32 of rod 29, into chamber 39 and thence downwardly through the bore 32 of rod 29 and back to the container i9. However, due to the relative restriction between the parts, only a small amount of liquid compared to the amount pumped will be returned to the drum or container I9 through the rod 29.

When the liquid in the drum has lowered to the lower end of the pump, that is, below the foot graan-r valve` 21;, air will enter the chamber 2T when the root, valve plate 29 lifts. As the piston, reciprocates, this air will be compressed slightly and will pass: from, chamberv 2&1, through aperture 43` in piston valve member 35, past the flat portion 32 of: rod 29, intok chamber 39 and thence downwardly through` the bore 32` of rod 29 and back to container I9.

Thepiston Valve spring 36` will prevent the pistonvvalve member 35 from,` opening, as the` pressure exerted against the piston valve member 35 is' very slight when` air is present in chamber 21. Thus, the air which enters. chamber 21 cannot passrinto chamber 29 from whence it would pass throught the measuring meter (not` shown) Only liquid pumped is, therefore, registered oni the meter; It will be apparent that no air which. passes into the chamber 39 may enter pressure chamber 2,6 because thetwo` chambers are sealed from eachother.

Operation of FiguresA 6 to 8 541- is.L forced'` outwardly under pressure through.l

passageway 11 to ameter 90. The foot valve plate l-ismaised from seat 5I- and liquid from container I9@ enters the chamber 55 through ports 6,0. Pistonvalve member 6:5 is closed.

@n.thedownward stroke ofrthe piston 59, foot valveplate 56 is; closed and piston valve memberv 65. is opened, thereby affording passage of the, liquid` from the lower chamber 55, throughchamber 63 pastthepiston valve member` 65 andi through openings 'I4r into upper chamber 5'4.` SlightA amounts of the liquidl pumped will pass throughv clearance 86 between the rod 83y and` valvefstemJS and into the bore 84 through slot. 85yA thence downwardly in the bore to below'the` foot.valve and into container I9. 'Ihe amount off liquid pumped back tocontainer I 9 will be small, however, `due to the relative restriction between the parts of the pump.V

Whenthe liquid levelin the container I9 falls belowthe foot valve 52, air will enter the cham ber^55` when the foot valveplate` Eli` opens. The

air: wilLbe under slight pressure as the piston 59' reciprocates, but the pressure will not be sufll4` cientto lift. the piston valve member 55 against" thefbiasi'of the valve spring 66. Air from'chamber` 55; therefore, passes through the clearance` ebetweenthe rod 83` and the valve stem` 'I9 and enters-the` chamber 8:2; passes through' notch 85 andzdownwardlythroughborell of rod 83 to container` I9. Anyl air which enters chamber 82 cannotenter pressurechamber 54- since these chambersarexsealed from each other. Therefore, no ,air'may-pass through outlet passage 'II and register onthemeter` 90.

, Operaatz'on of Figures 9 and 10 l Theaoperation of the pump perse is exactly` the' footvalve .plate 93;-isclosedand piston valvef Ill'Ilf is-openedf.: therebyalordingpassage: of liquidifromli 75 On the upward Stroker` the' niet chamber: sa, through passage` Ifn, past the: piston valve member IOT, and through the open-ings I I9 in casting IfIJ9 into the upper" cham# ber 91.

When the lubricant level in the container reaches the lower chamber 99 below the foot l stem ISIS-and plug III is sealed from thechamber 91S, noair may bepumped and only"7 liquid will register onl the` measuring meter.

Although there is a slightloss inefficiency in4 the pumping operationy due to some lubricant` being returned through bore I2-I` on each strblr'ef,V evenwhen no air is present, it is more important;

to insure that only lubricant substantially free of air passesthrough the measuring meter.

Itis to be noted that in all the embodimentsshown, the passage between thecylinder i'nlet" chamber and thefcontainer, including the passage through the vent-rod; is'relatively restricted compared with the passage through the piston'valves the majority ofthe lubricant through which pass'esl.`

Frornthe foregoing. it` will beapparent' that I- have provided improved pump construction which insures that liquid only will-be `pumped-andY registered on the measuring meter of apparatus ofthe type described Some changesrnay bemade in the construction and arrangement of the parts ofV my vent for pump without departing from the freal spiritand` .pur-poseiof myV invention, and it is my intentionv to cover? by my claims any modified forms of;

Structure or use of mechanical equivalents which` mavibeI-reasoii-ably included* within their scope-l without sacricingianyl of the advantagesthereof I! claim asrmyf invention: 1-1. Aliquid pump comprisingvafcylinder adapted to extendA atleast 4partially intosaid liquid, a. foot valve at the inlet portion ofthe cylinder, a4 pistonf=reciprocable in said=` cylinder, meansfor' recipro'catingsaidpiston, a valve carried bysaid piston dening avariable chamber below' sa'idL piston valveand a variable chamber abovesaid piston-valve, means for biasing said piston valveu inlone directionlin said-piston, a slidable hollow val-ve sterne-forfsaidipiston valve having its hollow` portion isolated fromlsaid chamber above said piston valve, a rod having' one endr extending throughj said"V foot` valve into the liquid" to be pumpe'dfandhavingits other end extending into'- the hollow-portion of said valve stem, means* provi'ding communication between said hollow portion'lof the valve stem and the portion of? the* cylinder b'elowfsaid piston valve,` means providing' communication between saidv hollow portionoi' saidl valve stem and the liquid below the foot valve",` andtan outletfrom said pump.

low portion isolated from said chamber above said piston valve, a rod having one end extending through said foot valve into the liquid to be pumped and having its other end extending into the hollow portion of said valve stem, means providing communication between said hollow portion of the valve stem and the portion of the cylinder below said piston valve, said rod being hollow to provide communication between said hollow portion of the valve stem and the liquid below the foot valve, and an outlet from said pump.

3. A liquid pump comprising a cylinder adapted to extend at least partially into said liquid, a foot -valve at the inlet portion of the cylinder, a piston reciprocable in said cylinder, means for reciprocating said piston, a valve carried by said piston dening a variable chamber below said piston valve and a variable chamber above said piston valve, means for biasing said piston valve in one direction in said piston, a slidable hollow valve stem for said .piston valve having its hollow portion isolated from said chamber above said piston valve, a rod having one end extending through said loot valve into the liquid to be pumped and having its other end extending mto the hollow portion of said valve stem, said rod including means providing communication be tween said hollow portion in the valve stein and said chamber of the cylinder below the said piston valve, means providing communication between said hollow portion of said valve stem and the liquid below said foot valve, and an outlet irom said pump.

A liquid pump comprising a cylinder adapted to extend at least partially into said liquid, a foot valve at the inlet portion of the cylinder, a piston reciprocable in said cylinder, means for reciprocating said piston, a valve carried by said piston defining a variable chamber below said piston valve and a variable chamber above said piston valve, means for biasing said piston valve in one direction in said piston, a slidable hollow valve stem for said piston valve having its hollow portion isolated from said chamber above said piston valve, a rod having one end extending through said foot valve into the liquid to be pumped and having its other end extending into the hollow portion of said valve stem, said rod including means providing communication between said `hollow portion in the valve stem and said chamber of the cylinder below the said piston valve, said rod being hollow to provide communication between said hollow portion of the valve stem and the liquid below the foot valve, and an outlet from said pump.

5. A liquid pump comprising a cylinder adapted to extend at least partially into said liquid, a foot valve at the inlet portion of the cylinder, a piston reciprocable in said cylinder, means for reciprocating said piston, a valve carried by said piston deim'ng a variable chamber below said piston valve and a variable chamber above said piston valve, means for biasing said piston valve in one direction in said piston, a slidable hollow valve stem for said piston valve having its hollow portion isolated from said chamber above said piston valve, a rod having one end extending through said foot valve into the liquid to be pumped and having its other end extending into the hollow portion of said valve stem, said rod including a reduced portion providing communication between said hollow portion in the valve stem and said chamber of the cylinder below said piston valve, means providing communication between 8 said hollow portion of said valve stem and the liquid below the foot valve, and an outlet from said pump.

6. A liquid pump comprising a cylinder adapted to extend at least partially into said liquid, a foot valve at the inlet portion of the cylinder, a piston reciprocable in said cylinder, means for reciprocating said piston, a valve carried by said piston dening a variable chamber below said piston valve and a variable chamber above said piston valve, means for biasing said piston valve in one direction in said piston, a slidable hollow valve stem for said piston valve having its hollow portion isolated from said chamber above said piston f valve, a rod having one end extending through said foot valve into the liquid to be pumped and having its other end extending into the hollow portion of said valve stem, said rod including a iat portion providing communication between said hollow portion in the valve stem and said chamber of the cylinder below said valve, means providing communication between said hollow portion of said valve stem and the liquid belowk tion isolated from said chamber above said piston valve, a rod having one end extending through said foot valve into the liquid to be pumped and having its other end extending into the hollow portion of said valve stem, means providing communication between said hollow portion of the valve stem and the portion of the cylinder below said piston valve, means providing restricted communication between said hollow portion of said valve stern and a location below the foot valve,

and an outlet from said pump.

8. A liquid pump comprising a cylinder adapted to extend at least partially into said liquid, a foot valve at the inlet portion of the cylinder, a piston reciprocable in said cylinder, means for recipro eating said piston, a valve carried by said piston dening a variable chamber below said piston valve and a variable chamber above said piston valve, meansfor biasing said piston valve in one direction in said piston, a slidable hollow valve stem for said piston valve having its hollow portion isolated from said chamber above said piston valve, a rod having one end extending through said foot valve into the liquid to be pumped and having its other end extending into the hollow portion of said valve stem, means providing communication between said hollow portion of the valve stem and the portion of the cylindery below said piston valve, means providing restricted communication between said hollow portion of said valve stem and a location below the foot valve,

said last means comprising a rod having a pas sage therethrough of less cross sectional area than the cross sectional area defined by said piston valve, and an outlet from said pump.

9. A liquid pump comprising a cylinder adapted to extend at least partially into said liquid, a foot valve at the inlet portion of the cylinder, a piston reciprocable in said cylinder, means for reciprocating said piston, a valve carried by said piston deiining a variable chamber below said piston .9 valve and a variable chamber above said piston valve, means for biasing said piston valve in one direction in said piston, a slidable hollow valve stem for said piston valve having its hollow portion isolated from said chamber above said piston valve, a rod lhaving one end extending through said foot valve into the liquid to be pumped and having its other end extending into the hollow portion of said valve stem, means providing communication between said hollow portion of the valve stem and the portion of the cylinder below said piston valve, means providing restricted communication between said hollow p-ortion of said valve stem and a location below the foot valve, said last means comprising a rod having a passage therethrough of less cross sectional area than the cross sectional area deiined by said piston valve, said rod being spaced a considerable distance from said valve stem and said piston having a relatively large passage centrally thereof communicating with the hollow portion of said valve stem, whereby unrestricted communication is aiorded between said chamber below the piston valve and the hollow valve stem, and an outlet from said pump.

10. A liquid pump comprising a cylinder adapted to extend at least partially into said liquid, a foot valve at the inlet portion of the cylinder, a piston reciprocable in said cylinder, means for reciprocating said piston, a valve carried by said piston defining a variable chamber below said piston valve and a variable chamber above said piston valve, means for biasing said piston Valve in one direction in said piston, a slidable hollow valve stem for said piston valve having its hollow portion isolated from said chamber above said piston valve, a rod having one end extending through said foot valve into the liquid to be pumped and having its other end extending into the hollow portion of said valve stem, means providing communication between said hollow portion of the valve stem and the portion of the cylinder below said piston valve, and providing restricted communication between said hollow portion of said valve stem and a location below the foot valve, said last means comprising a rod having a passage therethrough of less cross sectional area than the cross sectional area defined by said piston valve, said rod being spaced a considerable distance from said valve stem and said piston having a relatively large passage centrally thereof communicating with the hollow portion of said valve stem, whereby unrestricted communication is afforded between said chamber below the valve and the -hollow valve stem, the interior of said hollow valve stem being sealed off from said chamber above the piston valve, and an outlet from said pump.

11. A liquid pump comprising a cylinder adapted to extend at least partially into said liquid, a foot valve at the inlet portion of the cylinder, a piston reciprocable in said cylinder, means for reciprocating said piston, a valve carried by said piston dening a variable chamber below said piston valve and a variable chamber above said piston valve, means for biasing said piston valve in one direction in said piston, a slidable hollow valve stem for said piston valve having its hollow portion isolated from said chamber above said piston valve, a rod having one end extending through said foot valve into the liquid to be pumped and having its other end extending into the hollow portion of said valve stem, means providing communication between said hollow portion of the valve stem and the portion of the cylinder below said piston valve, means providing restricted communication between said hollow portion of said valve stem and a location below the foot valve, said last means comprising a rod having a passage therethrough of less cross sectional area than the cross sectional area dened by said piston valve, said rod being secured to said foot valve, and an outlet from said pump.

12. A liquid pump comprising a cylinder adapted to extend at least partially into said liquid, a foot valve at the inlet portion of the cylinder, a piston reciprocable in said cylinder, means for reciprocating said piston, a valve carried by said piston defining a variable chamber below said piston valve and a variable chamber above said piston valve, means for biasing said piston valve in one direction in said piston, a slidable hollow valve stem for said piston valve having its hollow portion isolated from said chamber above said piston valve, a rod having one end extending through said foot valve into the liquid to be pumped and having its other end extending into the hollow portion of said valve stem, means providing communication between said hollow portion of the valve stem and the portion of the cylinder below said piston valve, means providing restricted communication between said hollow portion of said valve stem and a location below the foot valve, said last means comprising a rod having a passage therethrough of less cross sectional area than the cross sectional area defined by said piston valve, and an opening in the side of the rod communicating with the passage therethrough, and an outlet from said pump.

13. A liquid pump comprising a cylinder adapted to extend at least partially into said liquid, a foot valve at the inlet portion of the cylinder, a piston reciprocable in said cylinder, means for reciprocating said piston, a valve carried by said piston defining a variable chamber below said piston valve and a variable chamber above said piston valve, means for biasing said piston valve in one direction in said piston, a slidable hollow valve stem for said piston valve having its hollow portion isolated from said chamber above said piston valve, a rod having one end extending through said foot valve into the liquid to be pumped and having its other end extending into the hollow portion of said valve stem, means providing communication between said hollow portion of the valve stem and the portion of the cylinder below said piston valve, means providing restricted communication between said hollow portion of said valve stem and a location below the foot valve, said last means comprising a rod having a passage therethrough of less cross sectional area than the cross sectional area defined by said piston valve, and an opening in the side of the rod communicating with the passage therethrough, said opening being in the form of an elongated notch in the side of said rod, and an outlet from said pump.

CHARLES W. GINTER.

REFERENCES CITED `The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 34,444 Old Feb. 18, 1862 56,380 Crawford July 17, `1866 FOREIGN PATENTS Number Country Date 461,468 Great Britain Feb. 17, 193']` 

